Method and apparatus for fast link setup in a wireless communication system

ABSTRACT

A method and apparatus for a communication system provide for fast link setup for a mobile station by transmitting a request message, transmitting an assignment message from the base station to the mobile station, and transmitting a notification message from the base station to a base station controller. The mobile station transmits an indication message to the base station controller indicating a successful completion of acquiring the data packet channel. The base station controller processes the indication message for message integrity and security feature. A portion of the available communication resources at the base station is allocated for an immediate response to the request message for acquiring a data packet channel.

CROSS REFERENCE

This application claims priority of U.S. Provisional Application Ser.No. 60/469,976, filed May 12, 2003 entitled “Method and Apparatus forControlling and Operating State of Mobile Station in a CommunicationSystem.”

FIELD

The present invention relates generally to the field of communications,and more particularly, to wireless communications.

BACKGROUND

A system of protocols normally controls the ways a mobile station and abase station may operate in a communication system. Such protocols aredisclosed in a set of standards published by a recognized standard body.The protocols may define a set of procedures for setting up acommunication link between a mobile station and a base station.Generally, such a procedure provides for establishing a reliable andsecure communication link. The process for establishing a link mayrequire assigning resources, such as Walsh code assignment, data rateand power level assignment, etc. In addition, the request forestablishing a communication link is processed for checking forintegrity of the end user device requesting establishment of the link.Moreover, the link may require having a security feature for securecommunications.

A system for communications of data benefits greatly by providing a fastlink set up procedure. In such a system, a mobile user is able to set upa communication link in a very short period of time, thus enhancing theuser experience of the communication systems. Therefore, there is a needfor providing a fast link set up in a communication system.

SUMMARY

A method and apparatus for a communication system provide for fast linksetup for a mobile station by transmitting a request message, foracquiring a data packet channel, transmitting an assignment message, andtransmitting a notification message from the base station to a basestation controller, wherein the notification message informs the basestation controller of a process for acquiring the data packet channel.The mobile station after acquiring the data packet channel transmits anindication message from the mobile station to the base stationcontroller indicating a successful completion of acquiring the datapacket channel. The base station controller processes the indicationmessage for message integrity at the base station controller. A radiolink release message is transmitted from the base station controller tothe base station in response to detecting a failure of the mobilestation in passing the message integrity process. The resourcesallocated to the acquiring the data packet channel are released inresponse. Furthermore, the indication message is processed for securityfeature at the base station controller. A radio link release message istransmitted from the base station controller to the base station inresponse to detecting a failure of the mobile station in passing thesecurity feature process, and releasing the allocated resources inresponse. A portion of the available communication resources at the basestation is allocated for an immediate response to the request messagefor acquiring a data packet channel.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of the present invention willbecome more apparent from the detailed description set forth below whentaken in conjunction with the drawings in which like referencecharacters identify correspondingly throughout and wherein:

FIG. 1 illustrates a communication system capable of operating inaccordance with various embodiments of the invention;

FIG. 2 depicts a flow of messages between several operating entities ina communication system for establishing a communication link; and

FIG. 3 depicts a flow of messages between several operating entities ina communication system for establishing a communication link inaccordance with various aspects of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Generally stated, various aspects of the invention provide for fast setup of a communication link between a base station and a mobile stationin a communication system by advantageously determining a partitioningof various portions of link set up processes over a number ofcommunication system operating entities. One or more exemplaryembodiments described herein are set forth in the context of a digitalwireless data communication system. While use within this context isadvantageous, different embodiments of the invention may be incorporatedin different environments or configurations. In general, the varioussystems described herein may be formed using software-controlledprocessors, integrated circuits, or discrete logic. The data,instructions, commands, information, signals, symbols, and chips thatmay be referenced throughout the application are advantageouslyrepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or a combinationthereof. In addition, the blocks shown in each block diagram mayrepresent hardware or method steps.

More specifically, various embodiments of the invention may beincorporated in a wireless communication system operating in accordancewith a communication standard outlined and disclosed in variousstandards published by the Telecommunication Industry Association (TIA)and other standards organizations. Such standards include the TIA/EIA-95standard, TIA/EIA-IS-2000 standard, IMT-2000 standard, UMTS and WCDMAstandard, GSM standard, all incorporated by reference herein. A copy ofthe standards may be obtained by writing to TIA, Standards andTechnology Department, 2500 Wilson Boulevard, Arlington, Va. 22201,United States of America. The standard generally identified as UMTSstandard, incorporated by reference herein, may be obtained bycontacting 3GPP Support Office, 650 Route des Lucioles-Sophia Antipolis,Valbonne-France.

FIG. 1 illustrates a general block diagram of a communication system 100capable of operating in accordance with any of the code divisionmultiple access (CDMA) communication system standards and GSM standardwhile incorporating various embodiments of the invention. Communicationsystem 100 may be for communications of data, or data and voice.Generally, communication system 100 includes a base station (BS) 101that provides communication links between a number of mobile stations,such as mobile stations (MS) 102–104, and between the MS 102–104 and apublic switch telephone and data network 105. In various specifications,a MS may be referred to as a user equipment (UE), and a BS as Node B.Therefore, such terms may be interchangeable without departing fromvarious aspects of the invention. BS/Node B 101 may include a number ofcomponents, such as a base transceiver system and antenna system. Forsimplicity, such components are not shown.

BS/Node B 101 may be in communication with other BS/Node B, for exampleBS/Node B 160, through a base station controller system (BSC) 199. TheBSC 199 may be referred to as radio network controller (RNC) in variousstandards. BSC/RNC 199 may control various operating aspects of thecommunication system 100 and in relation to communications over aback-haul between network 105 and BS/Node B 101 and 160. BS/Node B 101communicates with each mobile station that is in its coverage area via aforward link signal transmitted from BS/Node B 101. The forward linksignals targeted for MS/UE 102–104 may be summed to form a forward linksignal 106. Each of the MS/UE 102–104 receiving forward link signal 106decodes the forward link signal 106 to extract its intended receivedinformation. BS/Node B 160 may also communicate with the mobile stationsthat are in its coverage area via a forward link signal transmitted fromBS/Node B 160. MS/UE 102–104 communicate with BS/Node B 101 and 160 viacorresponding reverse links. Each reverse link is maintained by areverse link signal, such as reverse link signals 107–109 for mobilestations 102–104, respectively. The reverse link signals 107–109,although may be targeted for one BS/Node B, may also be received atanother BS/Node B. Various aspects of the invention provides forestablishing a link between a MS/UE and a BS/Node B in a quick mannerwhile complying with integrity and security features of thecommunication system 100.

Referring to FIG. 2, a flow chart 200 of a few exemplary messages forestablishing a communication link that are communicated between a MS/UE,a BS/Node B and BSC/RNC 199 are shown. Generally, setting up a linkinvolves at least three distinct operations. The first operation isassignment of channel resources, such as Walsh code assignment, datarate, communication layer 2 configurations, etc. The power level istypically managed and assigned by the BS/Node B directly via closed looppower control. The second operation is authenticating the requestmessage (message integrity function) to access the system to receivecommunication services. The third operation is for providing securityfeature of the communication link. These three operations take time inthe order of 100 to 400 msec. As such, establishing a link with aBS/Node B may take some time. A MS/UE may send a request to a BS/Node Bto start establishing a communication link. Such a request message maybe sent based on a previously received page message (not shown) fromBS/Node B. The BS/Node B passes the request message to BSC/RNC. One ormore communications may take place between BSC/RNC and BS/Node B forcompleting the process for defining all the configuration parametersnecessary for establishing a communication link. The BSC/RNC generatesthe configuration message. The BS/Node B sends the configuration messageto the MS/UE. After MS/UE receives the configuration message, the MS/UEbegins a process for acquiring a data packet channel (DPCH), andgenerates and sends a configuration-complete message after successfullycompleting the process for acquiring the DPCH. In the mean time, theBSC/RNC starts a timer. The BSC/RNC generally expects to receive theconfiguration-complete message within a time period measured by thetimer. After receiving the configuration-complete message, the BSC/RNCverifies the message integrity and stops the timer. If the integrity ofthe message fails, the message is discarded (ignored). If the timerexpires, the BSC/RNC would send a message (not shown) to BS/Node B toterminate the link with the MS/UE. In response, BS/Node B stopstransmitting to the MS/UE and stops reception on the DPCH on the reverselink. As a result the MS/UE can not use the acquired DPCH.

Referring to FIG. 3, a flow chart 300 of messages provides a flow ofmessages communicated between a MS/UE, BS/Node B and BSC/RNC inaccordance with various aspects of the invention which allowspartitioning various link set up operations for establishing acommunication link in a quick manner. In accordance with various aspectsof the invention, the operations of channel resource assignment,authenticating the request message and providing security features arepartitioned over more than one entity in the communication system. Inone exemplary embodiment, the channel resource assignment is performedby BS/Node B, while the operations of authenticating the request messagethrough the message integrity function and providing security featuresare performed by BSC/RNC. The partitioned operations may runconcurrently or on an overlapping time periods or at different times. Inaccordance with message flow 300, a MS/UE sends a request message toBS/Node B. The BS/Node B in urgency sends an assignment message to theMS/UE informing it of the assigned resources for acquiring a DPCH. Atthe same time or shortly after, the BS/Node B sends a notificationmessage to BSC/RNC that the MS/UE is in the process of setting a linkthrough acquiring a DPCH. Once the BSC/RNC receives the notificationmessage, BSC/RNC starts a timer. The timer counts an amount of timelapsed from the time the notification message is received until anindication message is received from the MS/UE that it has successfullyacquired the DPCH. Once the indication message is received, the BSC/RNCverifies the integrity, and may perform the security feature operation.If the indication message is not received from the MS/UE before thetimer period expires, there is no need to perform the integrityverification and security feature operation. Moreover, if the messageintegrity fails, the message is discarded (ignored), and if the timerexpires, the BSC/RNC sends a message to the BS/Node B to release theradio link resources assigned to the MS/UE. In such a case, the MS/UE isunable to continue the communications with BS/Node B.

In accordance with various aspects of the invention, a MS/UE may be ableto set up a link through acquiring a DPCH very quickly while alsoallowing the BSC/RNC completing the process for verifying integrity ofthe MS/UE and providing security feature for the communication.Moreover, if communication resources are scarce at the time of therequest from the MS/UE and the MS/UE is not able to acquire a DPCH, theunavailability of the resources may become apparent to the MS/UE in amore timely manner than if all the operations had to be performed beforeattempting for acquiring a DPCH. In such a case, the MS/UE may repeatsending the request message until a maximum number of such messages aresent or until an assignment message is received before exhausting themaximum number of transmissions. The processes for checking integrityand security feature are performed after receiving a notification thatMS/UE has acquired a DPCH.

Base stations 101 and 160 may be simultaneously communicating to acommon MS/UE. For example, MS/UE 102 may be in close proximity ofBS/Node B 101 and 160, which can maintain communications with bothBS/Node B 101 and 160. On the forward link, BS/Node B 101 transmits onforward link signal 106, and BS/Node B 160 on the forward link signal161. On the reverse link, MS/UE 102 transmits on reverse link signal 107to be received by both BS/Node B 101 and 160. For transmitting a packetof data to MS/UE 102, one of the BS/Node B 101 and 160 may be selectedto transmit the packet of data to MS/UE 102. On the reverse link, bothBS/Node B 101 and 160 may attempt to decode the traffic datatransmission from the MS/UE 102. The data rate and power level of thereverse and forward links may be maintained in accordance with thechannel condition between the base station and the mobile station.Therefore, for such a case, the BSC/RNC 199 needs to manage thecommunication resources of both BS/Node B 101 and 160. Accordingly, inorder to maintain a level of control over the communication resourcesprovided by the BS/Node B 101 and 160, the BSC/RNC 199 allocates aportion of the available resources in each BS/Node B for autonomouscontrol by the BS/Node B. Such a portion of resources may be labeled asfast-setup resources. Therefore, when the BS/Node B receives a requestmessage from a MS/UE for link set up, the BS/Node B assigns resources tothe MS/UE from the fast-setup resources. Periodically, the BSC/RNC 199adjusts the level of fast-setup resources at each BS/Node B to balancethe available resources across all BS/Node B in the communication system100.

Generally, message integrity is needed for communications of databetween a MS/UE and BS/Node B. One or more of the messages communicatedbetween MS/UE and BS/Node B are made without message integrityprotection while the MS/UE is acquiring a DPCH. The indication messagetransmitted from the MS/UE is processed in accordance with a messageintegrity feature of the communication system. Therefore, the MS/UE mayneed to generate and process the indication message in accordance with amessage integrity process. The message integrity process is known andmore detailed in a 3GPP standard outlined as TS 33.102, section 6.5,incorporated by reference herein.

For security feature, MS/UE user data need to be protected. Such aprotection is provided through a security feature. Generally, the MS/UEand BSC/RNC process the information in accordance with a data cipheringprocess for security protection. The security feature process is knownand more detailed in a 3GPP standard outlined as TS 33.102, section 6.6,incorporated by reference herein. The security feature may or may nothave been set up between the MS/UE and MDC/RNC when the indicationmessage is sent from the MS/UE to BSC/RNC. Generally, the MS/UE may havemany different operating modes. The MS/UE may switch from a commonchannel communication to a dedicated channel communication or may add adedicated channel communication to an already existing common channelcommunication. Therefore, there may have been some communicationsbetween the MS/UE and BSC/RNC. If the security feature has been enabledat the time of sending the indication message in the messaging flow, theMS/UE may use the ciphering process to provide the security feature forthe indication message. Therefore, in accordance with various aspects ofthe invention, the MS/UE is able to switch from a common channelcommunication to a dedicated channel communication or may add adedicated channel communication to an already existing common channelcommunication in a very quick manner while providing the messageintegrity and security feature.

Handoff process is a well known and used process in a communicationsystem. Handoff processes are necessary since the MS/UE may be movingfrom one coverage area to another while maintaining a call connection.There are several types of handoff process. A soft hand off process is aprocess by which a MS/UE is able to continue receiving communications ina generally non-interruptive manner while the down link communicationsis being switched from a base station/Node B to another. A softer handoff process is a process by which a MS/UE is able to continue receivingcommunications in a generally non-interruptive manner while the downlink communications is being switched from one sector of a basestation/Node B to another sector of the same base station/Node B. ABS/Node B generally controls the availability of resources in allsectors of the BS/Node B. Therefore, the MS/UE may include theinformation about the channel conditions with various sectors of theBS/Node B in its request message for acquiring a DPCH. The BS/Node Baccordingly assigns from the fast-setup resources to setup a DPCH fromthe best suited sector. After the MS/UE has passed through a successfulmessage integrity process in response to sending the indication messageto the BSC/RNC, the BSC/RNC may find that the acquired DPCH may be bestsuited to be processed by another BS/Node B than the originally usedBS/Node B used to set up the DPCH. In such a case, the MS/UE is directedto use the new BS/Node for communication on DPCH. The BSC/RNC mayinitiate the hand off process from one BS/Node B to another. Theresources used to setup a DPCH in the new BS/Node B need not to be fromthe pool of fast setup resources at the new BS/Node B.

Those of skill in the art would further appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination. A softwaremodule may reside in RAM memory, flash memory, ROM memory, EPROM memory,EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or anyother form of storage medium known in the art. An exemplary storagemedium is coupled to the processor such that the processor can read,information from, and write information to, the storage medium. In thealternative, the storage medium may be integral to the processor. Theprocessor and the storage medium may reside in an ASIC. The ASIC mayreside in a user terminal. In the alternative, the processor and thestorage medium may reside as discrete components in a user terminal.

The previous description of the preferred embodiments is provided toenable any person skilled in the art to make or use the presentinvention. The various modifications to these embodiments will bereadily apparent to those skilled in the art, and the generic principlesdefined herein may be applied to other embodiments without the use ofthe inventive faculty. Thus, the present invention is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope consistent with the principles and novel features disclosedherein.

1. A method for a communication system comprising: transmitting arequest message, for acquiring a data packet channel, from a mobilestation to a base station; transmitting an assignment message, for saidacquiring said data packet channel, from said base station to saidmobile station; transmitting a notification message from said basestation to a base station controller, wherein said notification messageinforms said base station controller of a process of said acquiring saiddata packet channel; completing said acquiring said data packet channel;transmitting an indication message from said mobile station to said basestation controller indicating a successful completing of said acquiringsaid data packet channel; starting a timer at said base stationcontroller for measuring time expired after receiving said notificationmessage; transmitting a radio link release message from said basestation controller to said base station in response to detectingexpiration of said timer with respect to a timer threshold beforereceiving said indication message.
 2. An apparatus for a communicationsystem comprising: means for transmitting a request message, foracquiring a data packet channel, from a mobile station to a basestation; means for transmitting an assignment message, for saidacquiring said data packet channel, from said base station to saidmobile station; means for transmitting a notification message from saidbase station to a base station controller, wherein said notificationmessage informs said base station controller of a process of saidacquiring said data packet channel means for completing said acquiringsaid data packet channel; means for transmitting an indication messagefrom said mobile station to said base station controller indicating asuccessful completing of said acquiring said data packet channel; meansfor starting a timer at said base station controller for measuring timeexpired after receiving said notification message; means fortransmitting a radio link release message from said base stationcontroller to said base station in response to detecting expiration ofsaid timer with respect to a timer threshold before receiving saidindication message.